The Bengal paddler started on a positive note in the quarterfinal and clinched the first set 11-7, but Cai clawed his way back into the match by winning the second set 11-5.

However, Roy did not lose his heart and bagged the next three sets 12-10, 11-5, 13-11 in the best-of-seven contest and secured the final-four berth. In the semifinal, Roy will take on world number 17, Gao Ning, who beat another Indian A Amalraj 4-1 in other match.

Amalraj proved no match to Gao, who is considered to be the best Singapore paddler, and except in the second set he could not build up much resistance.

After losing the first set 1-11, he bagged the second 11-4, but went down 5-11, 5-11, 7-11 in the next three sets to crash out of the competition.

Meanwhile, India's experienced women pair of Poulomi Ghatak and Mouma Das came out with some determined performance to overcome Australian duo of M Miao and J F Lay 3-2 and entered the doubles semifinal.

But it was curtains for another Indian pair -- Kumaresan Shamini and Madhurika Patkar, who lost 1-3 to T Feng and Y Wang of Singapore.

In men's doubles, Olympian Achanta Sharath Kamal and former national champion Subhajit Saha also got the ticket to last-four stage after beating Nigeria's Aruna Akinade and A seun 3-1.

Another Indian pair of Amalraj and Roy, however, could not cross the quarterfinal hurdle and went down 0-3 to Singaporean duo of Gao and Zi Yang at the Yamuna Sports Complex.